https://cordova.apache.org/archive/docs/en/5.0.0/cordova/events/events.backbutton.html
backbutton - Apache Cordova
backbuttonapachecordova
https://forum.qt.io/topic/82143/qt-android-handling-backbutton-pressed
Qt android handling Backbutton pressed | Qt Forum
Aug 8, 2017 - How to minimize application on backkey pressed in android
qtandroidhandlingbackbuttonpressed